Dental device and method of utilizing the same



June 10, 19141. F. J. MOYLAN DENTAL DEVICE AND METHOD OF UTILIZING THE SAME Filed March 2, 1940 Patented June 10, 1941 DENTAL DEVICE AND METHOD OF UTILIZING THE SAME Francis J. Moylan, Scranton, Pa.

Application March 2, 1940, Serial No. 321,988

8 Claims.

This invention relates to the art of prosthetic dentistry and is particularly concerned with a method and apparatus for recording a bite in order to relate upper and lower casts to each other so that when mounted on an articulator they will have the same relation as the upper and lower jaws.

In devices of known construction, bite rims and face bows have been utilized and in general the apparatus used has been of rather complicated character. In addition, where recordings of the mandibular motion have been made, the apparatus employed has," to the best of my knowledge, involved the use of a stylus and a recording plate both of which are located outside of the mouth and consequently, due to the fact that such devices are visible. to the patient, they have the tendency to cause the patient to unconsciously move the jaws incorrectly in producing the record.

Furthermore, where bite rims are employed the friction between the same as the mandible is moved to positions of protrusive, and right and left lateral occlusion, caused inaccurate relative position of the maxilla and mandible with the result that faulty dentures are produced.

In making artificial dentures it is essential to take into consideration not only the vertical distance between the gum ridges but also the excursions of the mandible as it moves in the act of masticating. In order to accurately record. both the vertical distances and said excursions it is necessary that the mandible assume its most powerful relation, or central occlusion.

To insure such relation, my invention embodies the use of a relatively heavy spring interposed between the maxilla and mandible and positioned relative thereto so that in the act of taking a bite the condyles are forced to their highest point in the glenoid fossae and the main masticating muscles, such as the masseter, internal pterygoid and temporal muscles, are exerting their greatest force, such action insuring true centric occlusion.

My invention also insures true balanced occlusion because it is located centrally of the oral cavity so as to apply seating pressure throughout the supporting plates to the end that the plates will not tilt within the mouth.

In addition to overcoming the related objections of known devices, my invention possesses the advantage of simplicity, inexpensiveness, and accuracy in use which, together with the fact that it is located entirely within the mouth of the patient and consequently does not annoy or distract the patient, permits the making of artificial dentures with a minimum of adjustment of the articulator and grinding of the teeth.

Referring to the drawing, in which I have illustrated the preferred embodiment of my invention and in which corresponding parts are similarly numbered:

Figure 1 is a perspective view of my invention with parts disassembled to show the interiorconstruction.

Fig. 2 is a vertical central sectional view of the same.

Fig. 3 is a sectional view through the capsule taken on the line 3-3 of Fig. 2.

Fig. 4 is a top plan view of the lower supporting plate, and

Fig. 5 is a diagram of the recording on the record wafer.

With particular reference to the drawing, my invention embodies an upper plate I and a lower plate 2 which may be of vulcanite, shellac or other moldable base plate material shaped from casts of the gum ridges of the maxilla and mandible, respectively.

Attached to the upper plate I is a substantially T-shaped supporting plate 3, having each of its legs secured thereto in any desirable manner, such as by modeling compound at 4, 5 and 6.

The supporting plate 3 is curved both longitudinally and transversely to follow the contour of the vault l of the plate I but is spaced there-' from for reasons which will appear later.

At the intersection of the legs 4, 5 and 6 the supporting plate 3 is thickened as at 8 and is provided with a screw-threaded opening 9 to receive a threaded stem ill on the capsule ll.

' The space between the vault of the plate I and the supporting plate 3 permits the screw ID to project thereinto, so that'the screw l0 may be of a length suflicient to afford .a relatively large range of adjustment thereof together with the capsule ll carried thereby.

The capsule is locked in its adjusted position by means of a lock nut l2 provided with a finger piece l3 projecting outwardly beyond the capsule where it may be readily operated by the finger to lock or release the capsule.

The capsule l l consists of an inverted cupv It provided with a closed end i5 from which the screw l0 projects centrally.

Integrally formed on the side wall of cup M and projecting therefrom is a. rack It in a plane parallel to the axis of the cup and extending throughout the length thereof.

The cup I4 is also provided with a laterally projecting lug ll shown as being diametrically opposed to the rack l6, although such position is not essential as will be obvious.

ooperating with the upper cup I4 is a larger cup l8 telescoped over the cup I4 and havin a bottom wall i9 from which projects a centrally located stem 20 terminating in a semi-spherical stylus 2 The lower cup I8 is formed with offset ears 22 and 23 in a plane parallel to the axis of the cup and extending throughout the length thereof forming interior longitudinally extending grooves 2t and 25 which receive the rack l6 and lug l1, respectively, on the upper cup I 4.

Intermediate the ends of oifset ears 22 and 23 there are provided transverse slots 26 and 21 which receive a split, spring ring 28 terminating in hooks 29 and 30. The spring 28 closely engages the cylindrical portion of the cup l8 and extends across the grooves 24 and 25 so as to engage the rack I6 and lock the telescoping cups in position. The spring 28 likewise overlies the lug I1 and therefore prevents separation of the upper and lower cup members. The spring is released from engagement from the rack It by inserting the finger-nail under the hook 29 on the end. thereof and moving the spring out of the slot 26, and the cups may be separated by manipulating both hooks 29 and 30 as will be understood.

Interposed between the cups and bearing on the opposed walls I and I9 is a flat wound helical spring 3|, the co'nvolutions of the spring producing suflicient friction therebetween so that approximately 40 or 50 lbs. pressure is required to collapse the spring axially, it being understood that the spring is normally biased to expand axially to cause separation of the cups l4 and I8.

While I have described the inner upper cup I4 as carrying the rack and the lower outer cup It as carrying the ring 28, it is to be understood that these parts may be reversed and that the spring 3| may be of any type and strength so long as it accomplishes the desired results.

The lower plate 2 carries a table 32 by means of the legs 34, 35 and 36 attached thereto and to the plate. Upon the table 32 is a socket 31 receiving therein a wax recording wafer 38. Secured to the upper surface of the wafer is a thin, flexible metal disc 39 preferably of the thickness of foil so that it may readily flex to receive and record the impressions made by the stylus 2|.

It will be seen that by providing the semispherical stylus 2| which contacts the foil disc 39 there is no danger of the stylus adhering to the wafer 38 and that the force required to move the stylus over the record surface is reduced to a minimum as compared to the effort that would be required if a pointed stylus operating directly in the wax wafer were employed.

In use the capsule H is assembled and permitted to assume its expanded condition under the influence of the spring 3|. 'Ihesupporting plate 3 and the table 32 are attached to the plates I and 2, respectively, so that the capsule II and the table are located in the region of the second bicuspid and first molar teeth, with the recording table 32 centered with respect to the stylus 2|.

By locating the stylus and table at the mentioned location it will be seen that the principal masticating muscles operate on the mandible rearward of the table and in effect cause the mandible to fulcrum about the stylus so that the condyles are forced into their highest position in removed as a unit from the mouth. Attaching the upper and lower plates as described insures replacement of the plates in the mouth in their proper relation during subsequent operations.

After the attached plates I and 2 are removed from the mouth the wax recording wafer 38 is attached to table 32 by means of heat and then the plates and 2 are replaced in the patient's mouth, at which time the split ring 29 has been removed from the slot 23 so as to disengage the rack l6 and permit the capsule to assume its fully expanded position.

The capsule H is then adjusted by turning the screwa into or out of the threaded opening 9 until the stylus engages the foil disc 39 with the spring 3| expanded to separate the cups I4 and It. In this condition the patient can secure heavy compression on the spring as the maxilla and mandible move toward each other. The lock nut i2 is then operated to fix the capsule H in such position and the patient is instructed to move the mandible through the various movements required in mastication.

It will be seen that as the recording of the bite commences the movement of the mandible toward the maxilla forces the stylus into the wafer and, due to the resistance of the relatively strong spring 3| against which the patient is lting, the condyles are forced into their highest position in the glenoid fossae and the major masticating muscles are in position to exercise their greatest power, or in central occlusion.

As pressure of the mandible increases the spring 3| is overcome and the cups l4 and I8 telescope, at which time the rack |8 rides under the split ring 28 until the capsules have collapsed to an extent commensurate with movement of the mandible, after which it is locked in such collapsed position by the split ring 28.

Having thus determined the vertical dimension the mandible is moved to record protrusive, and right and left lateral occlusion. As these movements take place the stylus scribes the familiar gothic arch as shown in Fig. 5, it being noted that since the stylus is locked against downward movement, the recording will show the excursions of the mandible and that the groove traced by the stylus will be deepest at the intersection A and will gradually taper upwardly toward the surface of the disc 39 as the groove approaches the ends.

After the recording has been made the patient is instructed to hold the mandible motionless while the exact relation of the upper to lower plate is determined and if necessary, an impression can be made of portions of the plates so that when the plates and 2 are removed they can be placed together in exactly the same position as they were in the mouth of the patient.

The final steps involve placing casts in the upper and lower base plates, reassembling the said plates exactly as they were in the mouth, mounting the same in an articulator and adjusting the articulator in accordance with the record on the wax recording wafer, after which the device is removed from the casts and the teeth set up and finished by any of the known techniques.

From theforegoing description it is obvious that the method employed consists, in its broadest aspect, of forcing the condyles to their highest positions in the glenoid fossae by placing the mandible under load, determining vertical dimenaaiaass" sions and then, while in such position, recording the movements of which the mandible partakes in masticating.

From the foregoing it can be seen that by relatively simple mechanism I am able to establish: (1) true centric relation of the jaws; (2) mandibular excursions; (3) approximate vertical dimensions, and (4) balanced occlusion, and while I have illustrated one form of my invention it is a spring ring on the other cup engaging said rack to lock the cups in contracted position, a stylus carried by said capsule and a recording wafer carried by the lower plate beneath said stylus and cooperating therewith to record movements of the mandible thereon.

2. A device for recording a bite comprising a plate carried by the maxilla and a plate carried by the mandible, a supporting plate carried by the upper plate and having a threaded aperture therein, a capsule having a stem threading into said aperture by means of which the capsule may be adjusted relative to said upper supporting plate, a stylus on said capsule, said capsule comprising inverted telescoping cups, one of said cups carrying a rack on the wall thereof and extending in a plane parallel to the axis of the cup, the other cup having offset ears extending in planes parallel to the axis thereof to form longitudinally extending internal grooves, one of which re-' ceives said rack, the said offset portions carrying transverse slots and a spring ring disposed within the slots and engaging said rack bar, and a recording ,wafer supported on the lower plate beneath the stylus and in contact therewith to receive a record of mandibular movements.

3. A device for recording a bite comprising a,

a stylus on one of said plates and a recording wafer on the other plate receiving recordings from said stylus as the jaws are moved relative to each other, said recording wafer consisting of a disk of plastic material and a. thin, deformable, flexible, metallic disk adhered to the upper surface thereof and engaged by said stylus so as to deform but not wear or out under pressure of said stylus.

4. A device for recording a bite comprising a, plate carried by the maxilla and a plate carried by the mandible, a capsule mounted on the maxillary plate comprising telescoping cups normally biased to separated position, a rack on .one of said cups extendingparallel to the axis thereof and a spring ring on the other cup engaging said rack to lock the cups in contracted position, means for adjusting the capsule with reference to the plate carrying the same, a stylus carried by said capsule and a recording wafer carried by the lower plate beneath said stylus and cooperating therewith to record movements of the mandible thereon.

5. A device for recording a bite comprising a plate carried by the maxilla and a plate carriedby the mandible, a capsule mounted on the maxillary plate comprising telescoping cups normally biased to separated position, a rack on one of said cups extending parallel to the axis thereof and a spring ring on the other cup engaging said rack to lock the cups in contracted position, means for adjusting the capsule with reference to the plate carrying the same and means for locking said capsule in adjusted position, a stylus carried by said capsule and a recording .wafer carried by the lower plate beneath said stylus and cooperating therewith to record movements of the mandible thereon.

6. A device for recording a bite comprising a plate carried by the maxilla and a plate carried by the mandible, a. capsule mounted on the maxillary plate comprising telescoping cups normally biased to separated position, a rack on one of' said cups extending parallel to the axis thereof and a spring ring on the other cup engaging said rack to lock the cups in contracted position, means for releasing said locking means, astylus carried by said capsule and a recording wafer carried by the lower plate beneath said stylus and cooperating therewith to record movements of the mandible thereon.

'7. A device for recording a bite comprising a plate on the maxilla and a plate on the mandible,

retraction, said latch permitting free upward motion of the movable portion by action of the patients jaws and against the spring pressure on said movable portion and latching the movable portion against downward motion under spring action, and a recording wafer on the plate carried by the mandible in alignment with the stylus for recording movements thereof as the mandible is moved. I

8. A device for recording a bite comprising a plate on the maxilla and a plate on the mandible, a projectable and retractable stylus carried by the maxillary plate, said stylus including stationary and movable portions, spring means normally urging said portions away from each other, a spr. ing latch on one of said portions, said other portion having means thereon-en'gageable by said latch to hold the same in any of a number. of positions between complete projection and complete retraction, said latch permitting free upward motion of the movable portion by action of the patients jaws and against the spring pressure on said movable portion and latching the movable portion against downward motion under spring action, and a, recording wafer on the plate carried by the mandible in alignment with the stylus for recording movements thereof as the mandible is moved.

- FRANCIS J. MOYLAN. 

